1. Field of the Invention
The present invention relates to an image forming apparatus, such as a copying machine or a printer, using an electrophotographic method and a developing-agent amount detecting method, a cartridge used for the image forming apparatus, and a storage medium attached to the cartridge.
2. Description of the Related Art
Hitherto, an image forming apparatus such as a copying machine, a printer, or a facsimile machine develops an electro-static image which is formed on an image carrying member, such as an electrophotographic photosensitive member, by using a developing device and visualizes a developing-agent (hereinafter, referred to as toner) image.
The image forming apparatus, using the electrophotographic image forming process, uses a processing cartridge method by which the electrophotographic photosensitive member and processing means that operates to the electrophotographic photosensitive member are integrally used as a cartridge. The cartridge is detachable from the image forming apparatus. Further, the developing device used as a cartridge is put into practical use. According to the processing cartridge method, the user maintains the apparatus and therefore the operability is improved.
As one method for improving the usability of the processing cartridge, various technologies for detecting the remaining amount of toner for sending a notification indicating the remaining amount of toner of the processing cartridge to the user are well known. One of the well-known technologies for detecting the remaining amount of toner is a light-transmission-type method for detecting the remaining amount of toner and for measuring the transmission time of light that passes through a toner container for a predetermined time (refer to, e.g., Japanese Patent Laid-Open No. 10-186822 with reference to p. 6, FIGS. 7 to 8).
As the structure of the light-transmission-type method for detecting the remaining amount of toner, the image forming apparatus comprises a light emitting unit and a light receiving unit, a light-transmitting window is arranged to a toner container, a light guide introduces detected light between the light-transmitting window and the light emitting unit and light receiving unit, and the detected light passes through the toner container. The toner container has a stirring member which stirs the toner by rotating. In this case, when the remaining amount of toner is large and the stirring member is rotated, the toner shields the detected light. Thus, the detected light does not reach the light receiving unit. On the contrary, when the remaining amount of toner is small, the toner does not shield the light, and the light receiving unit detects the light. Since the time for light transmission in the toner container depends on the remaining amount of toner, the remaining amount of toner in the toner container is estimated by measuring the light-receiving time per rotation of the stirring member.
A signal processing unit samples an output waveform of an analog signal detected by the light receiving unit at a predetermined sampling interval. The signal is subjected to digital processing based on a predetermined threshold, and the light-detecting time per rotation of the stirring member is outputted as a pulse width. A relationship between the remaining amount of toner and the pulse width is checked in advance, thereby calculating the remaining amount of toner based on the pulse width. The relationship between the remaining amount of toner and the pulse width is stored in the image forming apparatus as a reference table or operation formula. In the light-transmission-type toner remaining-amount detection, in order to improve the precision thereof, the remaining amount of toner is calculated by a statistical method using statistical processing (refer to e.g., Japanese Patent Laid-Open No. 10-186822 with reference to p. 6, FIGS. 7 to 8).
The image forming apparatus needs to transfer and fix a toner image on various transfer members such as a thick sheet or OHT so as to form the image, and therefore has a plurality of printing modes having best sheet conveying velocities. In this case, a rotating velocity of the stirring member arranged in the processing cartridge is simultaneously changed. Thus, the rotating velocity of the stirring member in the toner container is changed. The absence of toner remaining-amount is accurately detected even when the rotating velocity of the stirring member changes. Therefore, in the image forming apparatus having a plurality of printing modes having different rotating velocities, a relationship between the light-transmission time corresponding to the rotating velocity and a threshold for determination of the absence of toner is obtained in advance (refer to Japanese Patent Laid-Open No. 2000-131936 with reference to p. 7, FIG. 3).
Recently, the processing cartridge has included a storage device. The main body of the image forming apparatus communicates information on image quality, manufacturing of processing cartridge, life of a member forming the processing cartridge, information on the used amount of toner, and information on operating status of the main body with the storage device. Thus, the maintenance of image forming apparatus or processing cartridge is easy and the usability is improved (refer to, e.g., Japanese Patent Laid-Open No. 10-133544 with reference to p. 10, FIG. 1).
However, the rotating period of the stirring member is usually between 0–10 RPM. As compared with the printing time of one transfer sheet, which is determined depending on the printing velocity of the image forming apparatus, in the case of the printing time of one printing sheet, the number of rotations of the stirring member is one to two RPM. Therefore, in the image forming apparatus having a plurality of printing velocities, in the image forming processing at varied printing velocities depending on one sheet, the stirring velocity of the stirring member is changed depending on the printing velocity of every sheet. The output waveform of the remaining amount of toner is sampled at a predetermined interval and then data for statistical processing every sheet has different-type data and thus an inaccurate value is calculated as the final remaining amount of toner.
The fluidity of toner varies depending on the printing velocity. Therefore, the light-transmission time changes in inverse-proportion to the rotating velocity. Further, upon changing the rotating velocity of the stirring member, the sampling interval varies depending on the rotating velocity in the signal processing, thus calculating the inaccurate time as the final remaining amount of toner.